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Re: Deleting undef values from a hash

by pg (Canon)
on Dec 14, 2003 at 05:04 UTC ( #314616=note: print w/ replies, xml ) Need Help??

in reply to Deleting undef values from a hash

This is probably the best result you can expect for now.

Ideally, in the world of modern computing, if you delete an element that does not exist, some sort of exception can be threw. Now, the two different cases become clearly distiguished:

  • If you delete an element that does not exist, you get exception;
  • If it exists, but has undef as value, no exception caught, but return undef (which is consistant with the way any defined value being handled)

For now, if you want to clearly distiguish the two cases (if there is a need), use exists() to check first, and only delete when the element really exists.

use strict; use warnings; $a = {"a" => 1, "b" => 2, "c" => undef}; print "c exists\n" if (exists($a->{"c"}));#c exists, although its valu +e is undef print "d exists\n" if (exists($a->{"d"}));#d does not exist

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